This allows the app to alter Framebuffer attachments while there are existing command buffers using the resources and attachments. BUG=angleproject:2200 Change-Id: I3298dafef5e3bd2c6efda8e8a32a6cf7febc13dc Reviewed-on: https://chromium-review.googlesource.com/742370Reviewed-by: Geoff Lang <geofflang@chromium.org>
